Photopolymerization of commercial photoresist SU-8 assisted by plasmonic near-field enhancement in nanogaps separating gold nanoblocks was investigated. Photopolymerization rates enhanced by orders of magnitude were found in gold nanoblock structures with nanogaps narrower than 10 nm. The mechanisms responsible for local and nonlocal nonlinear photopolymerization of SU-8 are discussed.

The authors acknowledge support from the KAKENHI Grant-in-Aid for Scientific Research on the Priority Area 'Strong Photon-Molecule Coupling Fields' (No. 470 (No. 19049001)) and 20710068, and Grants-in-Aid from Hokkaido Innovation through Nanotechnology Support (HINTS).